Dental crown-post extractor.



T. R. ARDEN. I DENTAL GROWN POST EX-TRAGTOR;

AAAAAAA TI'ON FILED MAR 25, 1914.

1,102,850. Patented July 7,1914.

human snares rarer orrrcn THOMAS RAYMOND ARDEN, or 'rr rrnannnrlara,PENNSYLVANIA, assrenon ro rr-rns, s. WHITE DENTAL MANUFACTURING COMPANY,a oonrona'rron or runn- SYLVANIA.

DENTAL CROWN-POST EXTRACTOR.

Patented July 7, ram.

Application filed March 25, 1914. Serial No. 827,108.

To allwhom it may concern:

Be it known that I, THOMAS RAYMOND ARDEN, a citizen of the UnitedStates, and a resident of the city of Philadelphia, county ofPhiladelphia, and State of Pennsylvania, have invented certain new anduseful Improvements in Dental Crown-Post Extractors, of which thefollowing is a specification, reference being had to the accompany ingdrawings. I

My invention relates particularly to implements for extracting dentalcrown-posts from tooth roots, .and to the method of preparing suchcrown-posts so as to be readily and securely engaged by the extractor.

In crowning a tooth it is the usual practice to provide a crown with apin or post having one end embedded therein and the other end projectinginto a suitably prepared cavity in the natural tooth root, in which itis cemented, and, obviously, undue pressure upon the crown so fracturesthe crown-post that it may be accidentally broken off flush with, orsometimes below, the ground surface of the natural tooth root, andtherefore is very difficult to extract from its embedded position insaid tooth root, for the purpose of replacing it with a newcrown-post,without cutting away a portion of the body of said root.

The principal object of my invention is to provide a crown-postextractor that may be securely attached to any crown-post withoutcutting away or removing any portion of the natural tooth body, and thatmay be conveniently manipulated to with draw the crown-post withoutdanger of fracturing said tooth body, and without pain, annoyance, orinconvenience to the patient.

Other objects of my invention are, to provide a crown-post extractorwith a member which may be securely connected in threaded relation witha crown-post to be extracted; and to provide means for forcing saidmember and the attached crown-post from the tooth root.

My invention comprehends a crown-post extractor having a threaded stemarranged to be connected in threaded engagement with a crown-post whichis embedded in a natural tooth root, and provided with a thumb-nutarranged to be supported by the ground surface of the said tooth root,against whichit l is forced when rotated to effect the withdrawal ofsaid crown-post.

My invention further includes all of the various novel features ofconstruction and arrangement as hereinafter more definitely specified.

In the accompanying drawings, Figurel is a central vertical sectionalview of a convenient embodiment of my improved extractor as applied toan embedded broken crown-post; Fig. 2 is a central vertical sectionalview of a natural tooth root having .a broken pin embedded therein; Fig.3 is a view similar to Fig. 2, but showing a shank formed on said pin;Fig. 4 is a view similar to Figs. 2 and 3, showing the shank threaded toreceive the threaded socket of the crownpost extractor.

The device shown in Fig. 1 comprises the externally threaded stem 5having the in: ternally threaded socket 6, and is provided with the head7 which may be conveniently milled so as to be readily rotated by theoperator to engage it with the threads 9 of the shank 10 formed on thecrown-post 11, which is embedded in the natural tooth root 12. he stem 5isprovided with a thumb-nut 15, which is in threaded engagement with theexterior threads of said stem, and which comprises the milled head 16and the cylindrical extension 17. The lower edge 18 of said extension 17is arranged to engage a suitable washer 20, preferably formed of metal,between which and the ground surface 21 of the natural tooth root may beinterposed a washer 22 of yielding material, such as rubber. Said washer22 distributes upon the natural tooth root any strain incident to therotation of the thumb-nut 15, in a direction tending to force the stem 5outwardly from said natural tooth root, which movement of said stemefiects the with drawal of the crown-post 11 from its embedded positionin said root.

The operation of withdrawing the crownpost from the tooth root may beeffected as follows z-lVhen the crown-post 11 is broken 0H substantiallyflush with the ground face 21 of the tooth root 12, as shown in Fig. 2,said post may be provided with the shank 10, as shown in Fig. 3, by anysuitable form of milling cutter whose external diameter does not exceedthe width of the crown-post 11, whereby the milling operation simplycuts away a portion of the metal of the crown-j'post to form the shank10, which, as best shown in Fig. 4:, may be provided with screw-threads9by any suitable thread-cutting die whose external diameter does notexceed the width of the crown-post 11. Having thus provided the shank 10with screw-threads 9, the post may be engaged with the internallythreaded socket 6 of the stem 5 by rotating said stem thereon to theposition shown in Fig. 1, wherein it forms a substantially integral partthereof, whereupon the nut may be rotated upon the stem- 5 until itengages the ground surface of the natural tooth root, preferably havingthe washers and 22 interposed to insure an even distribution of thepressure upon said natural tooth root. A further rotation of said nutobviously effects the withdrawal of the broken post from an embeddedposition in the root. It may be here noted that should the natural toothroot have its ground surface disposed in angular relation to the axis ofthe pin or post, the-washers 20-or 22 may be so shaped as to afford abearing surface normal to the axis of said pin for the engagement ofthelower or free bearing edge of the thumb-nut 15; in other words, eitheror both of these washers may be thicker upon one side than upon theother, or wedge-shaped. In some instances the Washers may be entirelyomitted and the bearing edge of said nut 15 be caused to bear directlyupon the ground surface of the tooth root. It is to be understood thatwhile I have described my extractor as being particularly applicable inthe extraction of crown-posts from tooth roots, without cutting away anyof the tooth body, it is obvious that it may as readily be employed inextracting broken drills, burs, etc, without cutting away any of thesurrounding body in which they may be embedded.

I do not desire to limit niy invention to the precise details ofconstruction and arrangement hereln set forth, as 1t 1s obvious thatvarious modifications may be made Copies of this patent may be obtainedfor five cents each, by addressing the A Washington, I). 0.

member having therein without departing from, the essential features ofmy invention as defined in the appended claims.

Having thus described my invention, I claim:

1. A crown-post extractor'comprising a member having threaded means forengaging a crown-post embedded in a tooth, and means for forcing saidmember from the tooth and thereby withdrawing said crownpost. 2. Acrown-post extractor comprising a an internally threaded socket arrangedto engage a crown-post embedded in a tooth, and ,means tending to bearupon said tooth to force said member from said tooth and therebywithdraw said crown-post. v, c p

8. A- crown-post extractor comprising a member having an internallythreaded socket for engaging a crown-post embedded in a tooth, and meansconnected with said 5 member and movably supported upon said tooth toforcesaid member from said tooth and withdraw said crown-post.

4:. A crown-post extractor comprising a member having an socket arrangedto be engaged with said crown-post in threaded relation therewith, andmeans rotatably connected with said member arranged to force it fromsaid tooth and thereby withdraw said crown-post.

internally threaded 5. A crown-post extractor comprising an externallythreaded stem having an internally threaded socket arranged to beengaged in threaded relation with a crownpost embedded in a tooth, and anut rotatably engaged with said external screwthreads, rotatable thereonto force said stem from said tooth and thereby withdraw said crown-postY In witness whereof, I have hereunto set my hand this 24th day ofMarch, A. D., 1914.

- THOMAS RAYMOND ARDEN.

Witnesses:

HARRY R. .BARBER, CLIFTON C. HALLOWELL.

Commissioner of Patents,

